Conclusion
In the present study, the influence of different concentration of
exogenous Ca to P. massoniana seedling growth was illustrated. Ca
deficiency resulted in significant growth and development inhibition
while adequate exogenous Ca promoted seedling growth and development.
The underling mechanisms were deciphered at physiological, proteomic and
transcriptional level (Figure 7). Exogenous Ca supply laid a foundation
for various Ca signal transduction pathways and intracellular Ca
homeostasis. Various primary metabolisms and basic biological process
including photosynthesis, carbohydrate metabolism/energy production and
nitrogen assimilation/protein metabolism were distributed by Ca
deficiency. Sufficient exogenous Ca restored and promoted these pathways
and processes through regulating the expression of enzymes and/or
proteins involved in these pathways and processes. Secondary metabolism
was activated as a result of improved primary metabolisms at high Ca
level. In addition, Ca deficiency leads to severe oxidative stress and
redox dyshomeostasis. Affluent exogenous Ca relieved this stress and
recover redox homeostasis. Moreover, cell wall structure
formation/strengthening and cell division processes were benefited by
exogenous Ca. Our study conferred a full view for the demonstration of
the potential mechanisms underlying exogenous Ca affected P.
massoniana seedling growth and development, which may serve as a useful
reference and guidance for both pinaceae plant scientific research and
pinaceae plant forestry industry.